Why can't i find any information about vlad IV, the son of (the impaler) vlad dracula III?

It seems to be that either everyone is completely confused about whether the impaler was vlad III or IV, or they don't see any significance to his son, or that there are no such records. The latter, I find difficult to believe. I'm sure that after Vlad Dracula: The Impaler's official death that his son did not simply fall off the face of the earth, and I would very much like to know what became of him.